Wildfires affect mesocarnivores habitat use and mammalian predator-prey relationships in a Mediterranean ecosystem

Abstract

Effects of fires on carnivores are still poorly understood, particularly in the fire-prone Mediterranean basin. For instance, whether the effects are mainly mediated by prey abundance (Prey Abundance Hypothesis, PAH), prey catchability (Prey Catchability Hypothesis, PCH) or habitat suitability is unclear. Our objective was to investigate the role of fire, mammalian prey abundance, habitat suitability and their interactions in shaping the use of space and time of two carnivores, i.e., the red fox Vulpes vulpes and the stone marten Martes foina. The study area was Monte Pisano (Italy), where 12 km2 of surface burned in 2018. In early summer 2021 a stratified random sampling design was implemented, with fire and forest type as main strata. Fifty sites were selected, and two infrared cameras were placed at each site. Camera data were used to develop single-species occupancy models for the two predators, whereas time overlap between theme and their prey was evaluated through the Mardia-Watson-Wheeler test. Fox occupancy decreased with increasing herbaceous cover, but only when “mouse and voles” abundance was medium to high, regardless of habitat type. Fox also had significant differences in temporal activity between burnt and unburnt areas, not coupled by a similar pattern for its prey. In contrast, stone marten occupancy mainly depended on canopy cover. The fox could have adapted its hunting strategy to features of the environment and prey abundance, somehow supporting both PCH and PAH. In time, this species could optimize its activity in burnt and unburnt areas according to the brightness of the night. Differences in activity in “mice and voles” were interpreted as anti-predatory responses to the fox. Lastly, the stone marten did not pursue its prey in open areas. In conclusion, carnivores’ habitat use and mammalian predator-prey relationships were overall influenced by fire and post-fire successions.